This invention relates to biochemistry and more particularly to an enzymatic preparation for the control of tumor growth and immune diseases, and a process of inserting said preparation into mammals.
Ample evidence has shown that the combination of certain peroxidases with hydrogen peroxide and a halide ion produces a system with strong cytotoxic properties. The myeloperoxidase-hydrogen peroxide-chloride system forms a potent cytotoxic system effective against bacteria, fungi, viruses, mycoplasma, and various mammalian cells. Similarly, the lactoperoxidase-hydrogen peroxide-thiocyanate system and the horseradish peroxidase-hydrogen peroxide-chloride system have been shown to have potent cytotoxic activities.
An equally cytotoxic system is obtained when instead of hydrogen peroxide, a hydrogen peroxide generating system is used. Thus, the glucose oxidase-horseradish peroxidase-chloride combination yields a potent cytotoxic system upon the addition of glucose. Galactose oxidase and xanthine oxidase have also been shown to be effective in this respect. Furthermore, we showed that the endogenous NADH oxidase activity of the horseradish peroxidase is also capable of promoting the cytotoxic activity of the enzyme in the presence of chloride ions.
A large body of evidence indicates that cytotoxic systems such as those described above may be operative in polymorphonuclear leukocytes, eosinophils, macrophages, and other cell types with cytotoxic properties. Such cells in general appear to utilize an NADH or NADPH oxidase as the peroxide-generating enzyme.
Macrophages are a necessary component in the augmentation of natural killer cell activity by Bacillus Calmette-Guerin (BCG) in mice. BCG also increases the peroxide and superoxide production by macrophages. The possibility thus exists that the peroxidase system of the macrophages plays a role in the augmentation of the natural killer cell activity. Similarly, peripheral lymphocytes, which are predominantly T-cells, contain a cytotoxic peroxidase. Chemiluminescence resulting from peroxide generating oxidative metabolism is observed when T lymphocytes are stimulated by Concanavalin A. Furthermore, immunization of mice with either soluble or particulate antigens causes an increase in peroxidase activity in the spleen which precedes the generation of specific antibody. These observations suggest that oxidase and/or peroxidase activity is in some way involved in developing specific immune responses.
Thus far none of the cytotoxic systems described above have been used in any in vivo experiments. However, some relevant experiments were done some time ago by Schultz and his colleagues. Schultz, Snyder, Wer, Berger and Bonner; Chemical Nature and Biological Activity of Myeloperoxidase: Molecular Basis of Electron Transport, Academic Press, New York, N.Y., pp. 301-321 (1972); and Schultz, Baker, and Tucker; Myeloperoxidase-Enzyme-Therapy of Rat Mammary Tumors; Cancer Enzymology, Academic Press, New York, N.Y. pp 319-334 (1976) Using mice bearing 20-methylcholanthrene induced tumors, these authors injected myeloperoxidase in combination with thio-TEPA, an antitumor drug. They observed a significant reduction in tumor growth in the treated mice, but no complete remissions. Neither myeloperoxidase nor thio-TEPA alone were effective in reducing tumor growth. The inhibition of tumor growth lasted as long as the treatment with myeloperoxidase and thio-TEPA was continued.
These results indicated that the activity of myeloperoxidase could play a role in the control of tumor growth, either directly or indirectly. Definite conclusions are difficult to obtain with such experiments, however, because the biological half-life of myeloperoxidase is only about 24 hours. It is noteworthy, that the toxic activity appeared to be specifically directed to the tumor tissue.